We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Comprehensive validation of the QA4ECV OMI NO2 climate data record with a harmonized MAXDOAS data set, and first TROPOMI NO2 operational validation results.
- Authors
Compernolle, Steven; Verhoelst, Tijl; Pinardi, Gaia; Granville, José; Hubert, Daan; Keppens, Arno; Niemeijer, Sander; Rino, Bruno; Boersma, Folkert; De Smedt, Isabelle; Eichmann, Kai-Uwe; Eskes, Henk; Hendrick, François; Lorente, Alba; Peters, Enno; Richter, Andreas; van Geffen, Jos; Van Roozendael, Michel; Wagner, Thomas; Lambert, Jean-Christopher
- Abstract
The QA4ECV NO2 1.1 tropospheric column climate data record (CDR) is one of threequality assured, atmospheric Essential Climate Variable (ECV) CDRs produced within theEC’s FP7 QA4ECV project, available on several sensors. In this work we report on thecomprehensive quality assessment and validation of this product on the OMI sensor. Thegeneric building blocks —developed or refined within the projects QA4ECV and EC’s H2020GAIA-CLIM and integrated in BIRA-IASB’s Multi-TASTE system and the QA4ECVvalidation server- are (i) a harmonized list of standard terms and definitions, relevantto the quality assurance of ECV Climate Data Records, (ii) a generic validationprotocol, virtually applicable to all atmospheric ECVs, and (iii) error classificationin the comparison, distinguishing between satellite errors, reference errors andcomparison errors. The QA4ECV validation server and Multi-TASTE components are thededicated validation tools. As reference data sets, we use (i) a harmonized NDACCMAXDOAS data set at 10 sites established within the QA4ECV project (QA4ECVMAXDOAS), providing column measurements, and (ii) a separate processing basedon optimal estimation, bePRO MAXDOAS, available at 3 sites, providing profilemeasurements. Application of the validation protocol results in the following conclusions regardingQA4ECV NO2 OMI 1.1. Data content study. The recommended quality filter causes a negative sampling bias inthe satellite product at the MAXDOAS sites, mainly due to the exclusion of clouded sceneswhich are associated with higher tropospheric NO2 concentrations. Information content study. A priori profile assumptions are quite different forMAXDOAS and satellite, and this has a significant impact on the retrieved columnvalues. Co-location, harmonization and comparison. The QA4ECV NO2 CDR displays anegative, seasonally varying bias with respect to the MAXDOAS reference, and -dependingon the site- a high comparison dispersion. Harmonization of the a priori profiles does notresolve the discrepancy. Part of the bias and comparison dispersion can be accounted forby the ex-ante satellite and reference uncertainties and comparison errors (i.e.,temporal/horizontal/vertical smoothing and sampling difference errors). Some types ofcomparison error, like the horizontal smoothing difference error, likely contribute to thenegative bias at some sites but not all. For some sites, part of the bias and comparisondispersion remains unexplained. While the QA4ECV and GAIA-CLIM projects have ended, experience and toolsdeveloped within are re-used in the ongoing validation of S5p TROPOMI. For example, thevalidation server from the Validation Data Analysis Facility of the S5p Mission PerformanceCentre (S5p-MPC-VDAF) is an extended and automated evolution of the QA4ECVvalidation server. S5p TROPOMI NO2 validation results, both from S5p-MPC-VDAF andfrom the S5PVT project NIDFORVal (S5P NItrogen Dioxide and FORmaldehyde Validationusing NDACC and complementary FTIR and UV-Vis DOAS ground-based remote sensingdata) are presented here, using as reference data NDACC MAXDOAS, ZSL-DOAS anddirect sun DOAS to validate respectively tropospheric, stratospheric and total NO2column.
- Subjects
SAMPLING errors; NITROGEN dioxide; CLIMATOLOGY; DATA analysis; QUALITY assurance
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article